After making stokes with the robobrush, the preview goes black for a moment and then when it reappears, it shows the results of the new foreground segementation. Sometimes when zoomed into a specific region the strokes made improve the segemtation boundary in that region. However, when zooming out, often I notice that the strokes also had an effect on the segementation in regions far away from where I made the new strokes. It would be really handy if there were a thumbnail somewhere that colour codes pixels that have been added and removed from the foregorund as a result of the last stroke.